(A) Field of the Invention
The present invention relates to a dental floss device, particulary a dental floss device with a guide post for use in flossing between teeth having a fixed orthodontic appliance extending between the teeth. This invention also relates to a method of producing such dental floss device.
(B) Description of the Prior Art
Dental floss is used to remove food debris and dental plaque on teeth by inserting between two teeth, extending to gingival sulcus, and then sweeping on teeth surface. It is an effective way to clean proximal surface between any two teeth in addition to the use of a tooth brush, and an effective tool to prevent from proximal caries and periodontities. However, in the course of orthodontic treatment, where a fixed orthodontic appliance is used, a metal wire fixed between teeth would prevent from passing through of the dental floss for cleaning of the tooth surface. There is a kind of flossing device with a hardened tip or needle-like tip for cleaning beneath fixed bridge, but its insertion to the small gap between a tooth and an orthodontic arch wire always causes injury to gums. Moreover, its tip in the form of a pin point can not provide any feeling about the depression area between teeth, and therefore a mirror should be used to find its position. It is quite inconvenient to use such dental flossing device.
Many prior art devices provide various dental floss threaders for different purposes, but most of which are intended for the use of threading floss between teeth for normal care of oral hygine. U.S. Pat. No. 5,050,625 to Siekmann, for example, discloses a threading device formed of a tube including a handle portion and a blade-like portion with a dental floss detachably retained therein. There are several disadvantages in the Siekmann disclosure. Such device with tapered blade-like portion is rendered harmful for gum tissue and is not applicable for flossing between the clearance formed between teeth and the orthondontic appliance. Moreover, each cleaning location requires a new threading device.
U.S. Pat. No. 4,326,547 to Verplank, and U.S. Pat. No. 4,011,658 to Tarrson et al disclose dental floss devices for cleaning the gap between teeth. U.S. Pat. No. 5,094,255 to Ringle discloses a dental floss device to remove plaque in the sulcus area of one's mouth. This device has a leader tapering to a point remote from the floss. The point end of such design is hurtful when not used carefully. Such device is not applicable for orthondontic patients because the diameter of the end which attaches to multiple strands of floss must be quite large. Therefore, patients under orthodontic therapy cannot feel the correct dimension of the clearance between teeth and the orthodontic arch wire simply by the aid of the point end. The correct dimension of the clearance can only be felt when the whole device has been passed through the clearance. The orthodontic appliance is likely to be pushed away from the teeth and falls off owing to an excessive force applied by the user to pull the larger diameter portion of the device through the clearance.
As to the method for producing dental floss devices, U.S. Pat. 5,094,255 to Ringle, for example, put a strand of fiber between an upper portion and a lower portion of a mould, each of the portions having corresponding peaks which form the point ends of two leaders when the mould is closed. Before injection of resin material, the mould close and the fiber will be raised. Problems thus appear as follows:
A. When the mould closes, the fiber 21 will be moved to a position away from the center of the leader portion 22 as shown in FIG. 5(a) taken from the cross section of the tapered portion of the leader. Therefore, an excessive tension will be introduced into the fiber, particularly the point tip of the leader. It is very important that the fiber be surrounded with a resin material uniform in radial thickness, and that the fiber has a certain tension optimal to keep the fiber being in a straight line. Otherwise the floss in the resin material will wind along the leader as illustrated in FIG. 5(b) and is likely to fall off due to poor bonding between the floss and the leader resulted from the contraction of the floss or the pressure induced by the stroke of injected resin material.
B. The surface where the tip of a leader is separated from the tip of another leader after ejected from the mould will be rough and therefore will cause injury to gums.
Therefore the first object of the present invention is to provide a dental floss device which has a guide post of a uniform diameter for a user to feel the dimension of the clearance between teeth and orthodontic arch wire without the help of a mirror. If the front end portion can pass through the clearance without difficulties, the tail end portion with a floss will of course pass through easily.
The second object of the present invention is to provide a dental floss device whose guide post has a unibody moulded semi-spherical tip for protective purposes to gums.
Another object of the present invention is to provide a method of producing the dental floss device which is more easier and more economical of floss than known prior arts.